Question

Cells ensure that proteins are localized to their correct compartments through a variety of distinct mechanisms. Which of the following is true of protein targeting in prokaryotic cells?

		None of the above
		Proteins are synthesized on ribosomes in the nucleus
		Transport of mRNA and protein between the cytosol and nucleus is carried out by nuclear pores
		Signal sequences direct proteins to the endoplasmic reticulum

Answer 1

The correct answer is option 4 - Signal sequences direct proteins to the endoplasmic reticulum

Explanation: Prokaryotes do not have any membrane bound organelles including nucleus. so proteins are not synthesized in nucleus , but in cytoplasm and there is no option of transport of mRNA from nucleus to cytoplasm as is observed in eukaryotes. Signal peptides are a short peptide sequence which is usually 16-30 amino acid long and is located at the N-terminus in newly synthesized proteins This signal sequence helps proteins to move their target destination.